This invention relates generally to catheters adapted to be inserted into the cardiovascular system and, more particularly, to an improved guide catheter having a distal end portion for more precise and easier positioning in the left coronary artery.
Catheters are often advanced in the performance of medical procedures such as angioplasty to widen the lumen of a coronary artery which has become at least partially blocked by a stenotic lesion causing an abnormal narrowing of the artery due to injury or disease. In these techniques, an angioplasty catheter is usually introduced into the aorta and then the coronary artery through a previously placed guide catheter. To place the guide catheter in the coronary artery, the proximal end of the guide catheter is manipulated until its distal end is steered into the ostium of the coronary artery branching off from the aorta. Other therapeutic catheters such as atherectomy catheters may also be advanced through the guide catheter.
A commonly used guide catheter used in treatment of the left coronary artery is often referred to as a "Judkins" catheter which has a specially shaped distal end portion for facilitating insertion into the left coronary artery. The Judkins catheter, from proximal to distal end, comprises a long first straight portion, a 180 degree curved portion, a shorter second straight portion parallel to the first straight portion, a bend, and a distal tip portion perpendicular to the second straight portion. The Judkins catheter forms relatively large angles when inserted into the cardiovascular system.
An improvement on the Judkins catheter includes a straight portion followed distally by a curved portion, followed distally by a second straight portion, followed distally by a second curved portion, followed distally by a tip. This straight portion lies against the ascending aorta wall opposite the ostium of the left coronary artery, providing support for the catheter. This improved design allows for better coaxial alignment in the lumen of the selected artery.
An angioplasty or other therapeutic catheter advanced through a guide catheter having numerous transitions between the straight and curved portions, or curves of varying radii encounter some resistance to advancement at each of the transitions. More specifically, when a therapeutic catheter encounters a transition point or bend in a guide catheter, this results in a force by the guide catheter tending to make the intravascular catheter assume the path of the guide catheter. There is an opposite force by the intravascular catheter tending to make the guide catheter assume the path of the intravascular catheter. In the region of the ascending aorta, a therapeutic catheter advanced through the transitions in the guide catheter will tend to straighten out the guide catheter curve and dislodge the guide catheter tip portion from the ostium of the left coronary artery. If the tip is dislodged from the ostium, time consuming replacement of the tip of the guide catheter into the ostium may be required.